Production of motive power.



E, ASPINALIL PRODUCTION OY MUTIVE PO'WPH,

Patented Feb. 16, 1915.

UNITED STATES PATENT OFFICE.

FRANK BOULTON ASPINALL, 0F BLACKHEATH, LONDON, ENGL'AND.

PRODUCTION OF MOTIVE POWER.

Application filed October 11, 1912.

To 077 whom it m 0.1/ concern Be it known that I, FRANK BOULTONAsrixxm.. a subject of the King of Great Britain. and resident of 8'emyss road, Ilackheath. London, England, engineer, have invented newand useful Improvements in the lroduclion of Motive Power, of which tht`following is a specification.

The. principal object of this invention is to reduce the enormous heatlosses which at present take place even in the liest steam practice butit is also designed to reduce the heat losses in other heat carrierssuch as air used in motive power engines. To attain thisl end. I carryout a cycle of operations which enables the steam or other heat carrierto be utilized to better advantage in the engine and also permits therecovery and ,use over and over again ot' the greater part olE thtl heatwhich leaves the engine in the exhaust.

In the accompanying drawing. Figure l is the card of the cycle used in asteam engine in present da)v practice. Fig. 2 is the card of the cycleembodying my improvements. Fig. 3 is the card of the Carnot c vcle. Fig.4 is the card of the compression of= the exhaust steam used inaccordance with my improved cycle. Fig. 5 is a diagram showing the cycleof operations embodied in my invention, and Fig. G is a diagram of theplant which I propose to employ.

In the cycle used in a steam engine in present practice. if all the workis done in lone cylinder as shown diagrammatically in Fig. 1 of theaccompanying sheet of diagrams steam is admitted from a to cut oftl atb, expanded from b to c, exhausted from c to d and the remainder'compressed from d to a to fill in the clearances. But. in this method ofworking, enormous variations of temperature take place in the steamduring its passage through the cylinder and consequently in thetemperature ot' the metal which comes in contact with the steam. Thefact of the metal being a conductor of heat still further complicatesmatters. This and the inevitable clearances tend to reduce the workdone, below what is theoretically possible. In the best modern practicehowever, matters are improved to a certain extent by the steam beingsuperheated when received by the engine. It is evident that exactly thesame work would be done if the steam were admitted from e to f (see Fig.2)

Specification of Letters Patent.

Patented Feb. 16,1915.

Serial No. 725.243.

dropped in pressure from f to g when the exhaust opens. exhausted from(7 to h and compressed from L to e provided that the effective meanpressures were in each case the same and, as the temperature of thesteam would not vary to the same extent inside the cylinder' the metalwith which the steam comes in contact would also not vary to the sameextent, thus reducing the metal`s ill etfect. Again, as the pressure. ate is less than at u. less Weight of steam is required to till theclearances. I therefore propose to produce steam at the volume whichsteam containing no water and no superheat would have at the pressure g,but superheated to such a temperaturethat its pressure is nearly equal,equal. or more than equal to the pressure at e depending on thesuperheat, the

steam being then at a large volume per unit y ot' weight. ()r in otherWords I produce steam at a certain pressure and then. b superheating it,increase its volume til the volume is equal to the volume of steamcontaining no water and, no superheat at the pressure (y, the pressureremaining constant so that the steam occupies a large volume per unit ofweight. The steam thus produced I admit for the full stroke,;orapproximately so, at the initial pressure. It will he noticed. however.that if the steam or other motive fluid is in the condition stated whenadmitted to the engine that it is possible, provided it is considereddesirable or expedient to do so. to expand the steam while work is beingdone. either by cutting off or gradually throttling throughout thestroke. without altering the fact that the steam or other working fluidis always at such a large volume per unit of weight when doing work thatthe pressure necessar)y to do the work is principally. if not wholly.due to the super-heat or excess of heat present.

Now it is obvious that both with the ordinary method and also with myown so far as it has been herein described a large amount of heat iswasted which is in the exhaust. even although some is recovered by anexhaust steam feed water heater or from the hot well. I am aware thatheat is recovered from the exhaust in what is known as the Carnot cycleas shown' in Fig. 3. for steam is received from lr to l expanded from Zto m, condensed from m to the point n, that is until there is such aquantity of steam and Water at n that when the mixture is compressed tothe pressure k there is all water present at the temperature of steam atthe pressure k, this water then being turned again into steam. Butfinpresent day practice, practically, the same result is obtained by aneconomizer. Binary fluid engines have also been proposed-to utilize heatin the exhaust. To recover heat from the exhaust, I proceed in a totallydifferent way. As already'described I admit steam for the full strokefrom e to f, the steam being superheated to such an extent that if thesuperheat were removed, the pressure would not be that at e b'ut that atg so when the steam is exhausted from the engine, I abstract' thesuperheat dropping the pressure to g. The'steam is then, instead ofbeing condensed, drawn into a compressor, compressed to the pressure eand returned to the original steam space to be again superheated. Thesteam, after the superheat is removed is compressed, see Fig. 4 from oto p put into the original steam space from p to g, the clearance steamexpander from q tol r and fresh steam drawn into the compressor from 1to o. The card off the engine cylinder as shown in Fig. 2 thereforerepresents more work than the card off the compressorI cylinder as shownin Fig. 4. The difference' between the two cards less the frictonal lossis therefore available for external work. The fact that the heat in thesteam, after the removal of the superheat is returned to the originalsteam space, reduces the amount of heat which has to be provided tosuperheat the steam to the desired temperature. The heat in the steamwhen it reaches the pressure at 7) will also be more than when the steamis at the pressure at o, the amount depending upon the heat lost andgained during compression.

The work available for external use can` be varied by altering theamount of superheat which is abstracted from the steam before it iscompressed as this will vary the unount of work done in the enginecylinder by increasing or diminishing the back pressure and also byincreasing or diminishing the work absorbed in the compressor cylinderrelatively to the work produced in the engine cylinder. By this methodof governing, the temperature is always kept the same from e to f, butthere are other methods of governing, such as altering e and g and theadmission temperature, etc. I mention this, because it is impossible toconsider all the various purposes and conditions for which steam poweris required and the relations of capital economy to heat economy.

In the above description I have not dealt vwith any temperaturesy orpressures but in actual practice I should make the temperature ate asreasonably high as the conditions permit and if I were workingcondensing would make the pressure g as low as possible relatively tothe pressure at e so that such a mean pressure is obtained as to securea fair duty out of a given sized cylinder governing being done bythrottling and the steam being passed through a feedwater heater beforeit is condensed. When working differentially, however, that is on thedifference between the work produced in the engine cylinder and the Workabsorbedin the compressor cylinder, I should also work at the highestreasonable temperature but vary e and g according to circumstances.Shortly, to get the heat economy, I circulate the heat which is in thesteam after the necessary amount of superheat has been abstracted andthen, by adding and abstracting further heat, produce external work.

In Fig. 5 a diagram is given showing the cycle of operations, the steamcirculating in the direction of the arrows. Steam is produced in thesuperheater 2 its temperature and pressure being ascertained by the gagey and thermometer m near the point where it enters the engine. Itstemperature and pressure are such that if the superheat were removed thesteam would be at a much lower pressure. The steam then passes throughthe engine cylinder w giving a card as in Fig. 2. n admission tothecooler v the superheat is abstracted thus reducing the pressure inthe cooler below that of the pressure in the superheater. The steam nextcirculates to the point where it enters the compressor u its temperatureand pressure being ascertained by the thermometer t and gage s at thispoint. It is then drawn into the compressor, compressed to the pressurein th'e superheater (see card Fig. 4) and put into the superheater to beagain superheated. The steam during its passage through the cooler isnot condensed as it is always superheated, the amount of superheat whichis in the steam when it enters the compressor depending upon the load onthe engine. By suitable arrangements the weight of steam Withdrawn fromthe cooler equals the weight of steam which enters the cooler,precautions also being taken against any excessive heat losses in thecompressor especially at top load. It will be noticed that steam isbeing exhausted into and removed from the cooler at the same time andsteam is also entering and leaving the superheater at the same time, butthe actual steam leaving the superheater and cooler has entered thesuperheater and cooler some Strokes previously, the number of strokesdepending upon the relative volumes of the superheater, engine cylinder,cooler and compressor. A time interval is therefore allowed for thesteam to receive and lose superheat. The superheater volume is such thatthere is no considerable variation of pressure. When working with' thiscycle,

the external work does not depend upon the steam consumption as no steamis consumed, but upon the total heat which can be or may be added andabstracted during the circulation of the steam. The amount of thepossible external work can therefore be increased or decreased byaltering the total amount of heat which it is possible to add orabstract in a given time during the circulation of the steam.

In Fig. 5, if the maximum temperature in the superheater is a constantand the speed of the engine is constant making the volume of steampassing through the engine a constant, the weight of steam circulated ina given time can be increased or decreased by adding or abstractingsteam from the superheater, and. as the weight of steam circulatedvaries, the heat, which can be added and abstracted. varies` Of coursethe pressures in the superheater and the cooler increase if steam beadded but the difference hetween the two pressures also increases andlikewise the pressure effective for external work. Thus, more eX- ternalwork can be done but at the expenditure of more heat. For instance, ifsteam at 4 lbs. and 50 lbs. pressure are superheated to 500c F. theincrease of pressure will be more with the 50 lbs. steam because itsdensity is more.

It is evident that if the pressure in the superheater is increased tosuch an extent that there is no superheat when the steam enters theengine cylinder, the engine will not work as the pressures on the twosides of the engine piston will be the same or, if the pressure in thesuperheater is too low, all the work produced will be absorbed inovercoming friction. The best pressure to have in the superheaterdepends upon the maximum temperature allowed 1n the superheater, thepurpose and conditions which have to be met by the engine, and theconstructional details of the plant. By circulating a reasonable weightof steam reasonably sized cylinders can be used to get the work withoutabnormal maximum temperatures in the superheater. This method of Workingmay possibly be thought to approach more closely to that of a hot airengine, so it must not be confused with the proposals of Joule,Erickson, and Stirling ecause it is different in many essentialrespects, among others bein the fact that my steam is circulated an theback pressure on the engine can be varied instead of being kept atatmospheric pressure.

In Fig. 6, as an illustration a diagram is given of a generalarrangement for carrylng out my purpose but, as previously pointed out,in actual practice, the arrangement may be modified to suit theconditions which have to be dealt with. 1 is a boiler which may be verysmall as it is only required for starting up, for making good any lossof steam and for varying the pressure c if desired. As a mattei' offact, if the super heater is used as a flash boiler the boiler 1 can bereplaced by a feed tank. 2 is a valve which controls the admission ofsteam or water to the superheater. 3 is a valve which is kept closed atstarting up to prevent condensation in the pipes, but is opened fullbore when on load. 4 is the superheater; 5 the engine niainstop valve; 6a valve which enables steam to be passed through the super-heater tokeep it cool it' the engine is suddenly shut down and the dainpers onthe superheater are not suiiicient to keep the super-heater from beingoverheated. T and 8 are the thermometer and gage for ascertaining thetemperature and the pressure ot' the steam on admission to the enginecylinder. f) is the engine cyl inder which has no expansion valve but asimple valve to give a card shaped like in Fig. 10 is the exhaust pipebut il desired, the steam can be passed through a jacket on the enginecylinder after it is exhausted. l1 is the reheater or jacket to thesteam on its way to the superheater after it has been compressed; 12 thepoint where the steam leaves the reheater; 13 a valve which can beopened to the atmosphere before putting the engine on load and forblowing ofi' steam when shutting down. It can also be used, if necessaryto adjust the pressure in the cooler. 11 is a valve blowing steam intothe cooling water so as to warm up the cooling water and cooler beforestarting to the desired temperature. 15 and 15i are valves for shuttingoil1 steam from cooler till it has been warmed up, so as to preventwater accumulating in the cooler due to condensation. 17 and 18 are thegage and thermometer for ascertaining the temperature and pressure ofthe steam on admission to the com` pressor cylinder. 19 is thecompressor cylinder which gives a card shaped like in Fig. 4. 20 and 21are the thermometer and gage for ascertaining the temperature andpressure of the steam on leaving the compressor, the chief use of whichis to ascertain the steams temperature and pressure so as to tell ifeverything is warmed up thoroughly. Q2 is a valve to shut off steam fromthe pipe leading to the superheater when Warming up 23 a valve to allowsteam to be blown into the atmosphere when warming up; 24 is a valve toadjust the amount of water supplied to the cooling tank; 25 a drain fromthe tank containing the cooling water to run off the hot water whichwater, if desired, can be passed through a jacket on the compressorcylinder to reduce the heat losses in the compressor. By suitable meansthe abstraction of heat by the cooler can be governed according to theload.

In the method of warming up described, the engine is turning around, butby having suitable by-passes at the engine and compressor cylinders,this could be done with the engine standing. These also could be used soas to kee everything Warm if the engine is require to be constantlystopped and started. This arrangement also provldes means for Varyingthe pressures in the superheater and cooler on load if desired. Thecooling water may be used under pressure to get a higher temperature inthe compressor jacket, if desired. The cooler may be air cooled. Thecycle is the same when a carrier of heat other than steam is employed,minor differences only with different heat carriers being necessary.

In working according to my invention precautions should be taken to agreater extent than in an ordinary engine to prevent loss of heat byradiation or conduction.

What I claim and desire to secure by Letters Patent of the United Statesis 1. A method of producing motive power which comprises expandingworking fluid to a large volume by superheating it without altering itspressure, passing it through an engine in that condition, exhausting itwhile still superheated, abstracting the superheat, thus reducing thepressure, and compressing this reduced pressure steam to the originalpressure ready for superheating again.

2. A method of producing motive power which comprises compressingworking Huid to the desired pressure, expanding it to a large volume bythe addition of heat, passing it through an engine in that condition,exhausting it while still heated, removing the heat without materiallyaltering the volume and compressing it to the original volume ready fora fresh supply of heat substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

FRANK BOULTON ASPINALL.

Witnesses:

ALFRED V. BISHOP, R. WEs'rAco'rr.

